Non-return device

Abstract

A non-return device ( 10 ) for use with a waste trap is described. The non-return device comprises a sealing portion ( 12 ) having first and second sheet members ( 14, 16 ), a device inlet ( 18 ), a device outlet ( 20 ) and a transition portion ( 22 ) providing fluid communication between the device inlet and the sealing portion. The transition portion has a convex section of wall ( 24 ).

The invention claimed is: 
     
       1. A non-return device, the non-return device comprising:
 a sealing portion having first and second sheet members biased to a sealed position in which the first and second sheet members are at least partially in surface contact; 
 a tubular portion comprising a device inlet, wherein the tubular portion comprises a non-constant tubular length that depends on a circumferential position around the tubular portion, wherein the device inlet is a circular flange defining a circular opening, the circular flange comprising a thickened portion and acting to hold the device inlet open; 
 a device outlet; and 
 a transition portion providing fluid communication between the device inlet, the tubular portion and the sealing portion, the transition portion having a bowed-out convex section of wall for allowing a build-up of fluid within the non-return device in the transition portion in an immediate vicinity of the sealing portion; 
 wherein in use, the device outlet is oriented in a downwards position relative to the device inlet and fluid build-up in at least one of: the tubular portion and the transition portion forces the first and second sheet members apart to an open position; and 
 wherein the non-return device is a waste trap non-return device. 
 
     
     
       2. The non-return device of  claim 1 , wherein the sheet members are moveable from the sealed position to the open position, in which the sheet members are forced apart by a flow of fluid flowing from the device inlet to the device outlet, the sheet members being biased to return to the sealed position from the open position such that fluid is prevented from flowing from the device outlet to the device inlet. 
     
     
       3. The non-return device of  claim 2 , wherein the sheet members are biased to the sealed position by resilience. 
     
     
       4. The non-return device of  claim 1 , wherein the non-return device is injection moulded. 
     
     
       5. The non-return device of  claim 1 , wherein the non-return device is compression moulded. 
     
     
       6. The non-return device of  claim 1 , wherein the device inlet is biased to an open position. 
     
     
       7. The non-return device of  claim 1 , wherein the sheet members define a flow path from the transition portion to the device outlet. 
     
     
       8. The non-return device of  claim 7 , wherein the flow path is non-linear. 
     
     
       9. The non-return device of  claim 1 , wherein the sheet members define the device outlet. 
     
     
       10. The non-return device of  claim 1 , wherein the sheet members define at least one bend or kink. 
     
     
       11. The non-return device of  claim 10 , wherein the sheet members define a flow path from the transition portion to the device outlet, and wherein the bend or kink extends across the sheet members in a direction perpendicular to a direction of the flow path. 
     
     
       12. The non-return device of  claim 10 , wherein there is one kink. 
     
     
       13. The non-return device of  claim 10 , wherein the sealing portion comprises a plurality of sealing portion sections, each sealing portion section being adjacent, a bend or kink. 
     
     
       14. The non-return device of  claim 13 , wherein each sealing portion section is linear. 
     
     
       15. The non-return device of  claim 13 , wherein, where there is one kink, an angle between the sealing portion sections adjacent the kink is between 110° and 170°. 
     
     
       16. The non-return device of  claim 13 , wherein at least a portion of each sheet member is less than 0.5 mm thick. 
     
     
       17. The non-return device of  claim 16 , wherein the sheet member portion of each sheet member is adjacent a sealing portion section. 
     
     
       18. The non-return device of  claim 1 , wherein the sheet members are a variable thickness. 
     
     
       19. The non-return device of  claim 1 , wherein the non-return device comprises silicone. 
     
     
       20. The non-return device of  claim 7 , wherein each sheet member comprises a first edge and a second edge, the edges being parallel to the flow path. 
     
     
       21. The non-return device of  claim 20 , wherein the first sheet member first edge is joined to the second sheet member first edge and the first sheet member second edge is joined to the second sheet member second edge. 
     
     
       22. The non-return device of  claim 1 , wherein the first and second sheet members comprise at least one biasing member. 
     
     
       23. The non-return device of  claim 22 , wherein the first and second sheet members comprise at least one stiffening member. 
     
     
       24. The non-return device of  claim 23 , wherein the biasing members and the stiffening members are the same. 
     
     
       25. The non-return device of  claim 22 , wherein at least one of: the biasing members and stiffening members are first and second ribs. 
     
     
       26. The non-return device of  claim 25 , wherein the first rib connects the sheet member first edges and the second rib connects the sheet member second edges. 
     
     
       27. The non-return device of  claim 26 , wherein the ribs extend a full length of the sheet members. 
     
     
       28. The non-return device of  claim 26 , wherein the ribs bias the first and second sheet members to the sealed position. 
     
     
       29. The non-return device of  claim 25 , wherein each rib is more than 50% of a thickness of each sheet member. 
     
     
       30. The non-return device of  claim 25 , wherein each rib is more than 50% thicker than the sheet members combined. 
     
     
       31. The non-return device of  claim 25 , wherein the ribs extend up to the transition portion. 
     
     
       32. The non-return device of  claim 25 , wherein stiffening members are formed from a same material as the sheet members. 
     
     
       33. The non-return device of  claim 1 , wherein the sealing portion is injection moulded in a tool comprising a shell and a core. 
     
     
       34. The non-return device of  claim 33 , wherein the core is 0.2 mm thick. 
     
     
       35. The non-return device of  claim 33 , wherein the core includes a highly polished surface portion. 
     
     
       36. The non-return device of  claim 35 , wherein the sealing portion comprises an internal surface, and wherein the internal surface of the sealing portion is formed against the highly polished surface portion. 
     
     
       37. The non-return device of  claim 33 , wherein the moulding tool shell also comprises a polished surface portion. 
     
     
       38. The non-return device of  claim 37 , wherein the polished surface portion is in a region of the sealing portion. 
     
     
       39. The non-return device of  claim 1 , wherein the transition portion comprises:
 a first transition portion extending between a first side of the tubular portion and the first sheet member; and 
 a second transition portion extending between a second side of the tubular portion and the second sheet member, 
 wherein each of the first and second transition portions comprise a boundary defining a perimeter of the transition portion, the boundary comprising: 
 a tubular portion transition between the tubular portion and the transition portion; and 
 a sealing portion transition between the transition portion and the sealing portion, 
 wherein in use, fluid build-up between the first and second transition portions forces the first and second sheet members apart to the open position to allow fluid to exit the sealing portion via the device outlet. 
 
     
     
       40. The non-return device of  claim 39 , wherein the sealing portion, the tubular portion comprising the device inlet, the device outlet and the transition portion are formed from a same material. 
     
     
       41. The non-return device of  claim 39 , wherein at least part of the tubular portion extends between at least part of the sealing portion transition and the device inlet, wherein the tubular length extending between the device inlet and the sealing portion transition is greater than the tubular length extending between at least part of the device inlet and a corresponding part of the tubular portion transition. 
     
     
       42. The non-return device of  claim 39 , wherein the tubular portion comprises a plurality of different tubular lengths extending axially between the device inlet and at least one of: the tubular portion transition and the sealing portion transition. 
     
     
       43. The non-return device of  claim 39 , wherein each transition portion further comprises a concave section of wall. 
     
     
       44. The non-return device of  claim 43 , wherein the sealing portion transition comprises at least a portion of the concave section of wall. 
     
     
       45. The non-return device of  claim 43 , wherein the convex section of wall is disposed between the concave section of wall and the tubular portion transition. 
     
     
       46. The non-return device of  claim 43 , wherein each transition portion comprises a planar section of wall between the concave section of wall and the convex section of wall. 
     
     
       47. The non-return device of  claim 1 , wherein the sealing portion, the tubular portion comprising the device inlet, the device outlet and the transition portion are formed from a same material. 
     
     
       48. A non-return device, the non-return device comprising:
 a sealing portion having first and second sheet members at least one sheet member comprising at least one stiffening member biasing the first and second sheet members to a sealed position in which the first and second sheet members are at least partially in surface contact; 
 a tubular portion comprising a device inlet, wherein the tubular portion comprises a non-constant tubular length that depends on a circumferential position around the tubular portion, wherein the device inlet is a circular flange defining a circular opening, the circular flange comprising a thickened portion and acting to hold the device inlet open; 
 a device outlet; and 
 a transition portion providing fluid communication between the device inlet, the tubular portion and the sealing portion, the transition portion having a bowed-out convex section of wall for allowing a build-up of fluid within the non-return device in the transition portion in an immediate vicinity of the sealing portion; 
 wherein in use, the device outlet is oriented in a downwards position relative to the device inlet and fluid build-up in at least one of: the tubular portion and the transition portion forces the first and second sheet members apart to an open position; 
 wherein at least a portion of each sheet member is less than 0.5 mm thick; and 
 wherein the non-return device is a waste trap non-return device. 
 
     
     
       49. A non-return device, the non-return device comprising:
 a sealing portion having first and second sheet members, at least one sheet member comprising at least one biasing member biasing the first and second sheet members to a sealed position in which the first and second sheet members are at least partially in surface contact; 
 a tubular portion comprising a device inlet, wherein the tubular portion comprises a non-constant tubular length that depends on a circumferential position around the tubular portion, wherein the device inlet is a circular flange defining a circular opening, the circular flange comprising a thickened portion and acting to hold the device inlet open; 
 a device outlet; and 
 a transition portion providing fluid communication between the device inlet, the tubular portion and the sealing portion, the transition portion having a bowed-out convex section of wall for allowing a build-up of fluid within the non-return device in the transition portion immediately above the sealing portion; 
 wherein in use, the device outlet is oriented in a downwards position relative to the device inlet and fluid build-up in at least one of: the tubular portion and the transition portion forces the first and second sheet members apart to an open position; and 
 wherein the non-return device is a waste trap non-return device.